The present invention relates to a key-less entry system for locking/unlocking a vehicle door without inserting a key into a keyhole.
There are several types of key-less entry system for locking/unlocking vehicle doors by inserting a key into a keyhole.
One old type of key-less entry system employs a key equipped with a lock button and an unlock button for locking/unlocking vehicle doors by depressing these buttons.
In contrast, an advanced key-less entry system employs a portable communications device called a smart key, requiring no keyholes, for locking/unlocking vehicle doors.
In detail, vehicle doors are unlocked when a person such as a car owner carrying the smart key has approached a vehicle. The doors are then locked when he or she leaves the vehicle. The engine starts when he or she turns an engine-start knob while there is the smart key close to the vehicle.
The old type requires operations of depressing the lock and unlock buttons, thus inconvenient. The advanced type does not require any specific operations for locking/unlocking vehicle doors. The latter type, however, consumes power for always monitoring the smart key, thus escalating consumption of an in-vehicle battery and/or a battery installed in the smart key.
Moreover, the smart key forcefully unlocks vehicle doors when a person such as a car owner carrying the smart key has approached the vehicle, even though he or she does not want to do so.